Recently I reviewed some first posts. One post's formatting was pretty bad, so I choose "Edit", to improve it. On Stackoverflow I do not have to add a summary, because I've got enought reputation. However I forgot to fill in the summary in here, so the editing page informed me with a shaking dialog to fill it in. Right after the dialog showed up, the editing box duplicated: there was one with my changes and one with the original content. Strangely enought, also the button "Editing..." duplicated. It's hard to describe, but I've created a screenshot:
I was unable to reproduce this bug, because there were no reviews left.
Maybe you are able to reproduce it!